The present invention relates generally to process control systems within process plants and, more particularly, to the use of a coordinated expert system to aid asset utilization and optimization in a process plant.
Process control systems, like those used in chemical, petroleum or other processes, typically include one or more centralized or decentralized process controllers communicatively coupled to at least one host or operator workstation and to one or more process control and instrumentation devices, such as field devices, via analog, digital or combined analog/digital buses. Field devices, which may be, for example valves, valve positioners, switches, transmitters, and sensors (e.g., temperature, pressure and flow rate sensors), perform functions within the process such as opening or closing valves and measuring process parameters. The process controller receives signals indicative of process measurements or process variables made by or associated with the field devices and/or other information pertaining to the field devices, uses this information to implement a control routine and then generates control signals which are sent over one or more of the buses to the field devices to control the operation of the process. Information from the field devices and the controller is typically made available to one or more applications executed by an operator workstation to enable an operator to perform desired functions with respect to the process, such as viewing the current state of the process, modifying the operation of the process, etc.
While a typical process control system has many process control and instrumentation devices, such as valves, transmitters, sensors, etc. connected to one or more process controllers which execute software that controls these devices during the operation of the process, there are many other supporting devices which are also necessary for or related to process operation. These additional devices include, for example, power supply equipment, power generation and distribution equipment, rotating equipment such as turbines, etc., which are located at numerous places in a typical plant. While this additional equipment does not necessarily create or use process variables and, in many instances, is not controlled or even coupled to a process controller for the purpose of affecting the process operation, this equipment is nevertheless important to and ultimately necessary for proper operation of the process. In the past however, process controllers were not necessarily aware of these other devices or the process controllers simply assumed that these devices were operating properly when performing process control.
Still further, many process plants have other computers associated therewith which execute applications related to business functions or maintenance functions. For example, some plants include computers which execute applications associated with ordering raw materials, replacement parts or devices for the plant, applications related to forecasting sales and production needs, etc. Likewise, many process plants, and especially those which use smart field devices, include applications which are used to help monitor and maintain the devices within the plant regardless of whether these devices are process control and instrumentation devices or are other types of devices. For example, the Asset Management Solutions (AMS) application sold by Fisher-Rosemount Systems, Inc. enables communication with and stores data pertaining to field devices to ascertain and track the operating state of the field devices. An example of such a system is disclosed in U.S. Pat. No. 5,960,214 entitled xe2x80x9cIntegrated Communication Network for use in a Field Device Management System.xe2x80x9d In some instances, the AMS application may be used to communicate with devices to change parameters within the device, to cause the device to run applications on itself, such as self calibration routines or self diagnostic routines, to obtain information about the status or health of the device, etc. This information may be stored and used by a maintenance person to monitor and maintain these devices. Likewise, there are other types of applications which are used to monitor other types of devices, such as rotating equipment and power generation and supply devices. These other applications are typically available to the maintenance persons and are used to monitor and maintain the devices within a process plant.
However, in the typical plant or process, the functions associated with the process control activities, the device and equipment maintenance and monitoring activities, and the business activities are separated, both in the location in which these activities take place and in the personnel who typically perform these activities. Furthermore, the different people involved in these different functions generally use different tools, such as different applications run on different computers to perform the different functions. In many instances, these different tools collect or use different types of data associated with or collected from the different devices within the process and are set up differently to collect the data they need. For example, process control operators who generally oversee the day to day operation of the process and who are primarily responsible for assuring the quality and continuity of the process operation typically affect the process by setting and changing set points within the process, tuning loops of the process, scheduling process operations such as batch operations, etc. These process control operators may use available tools for diagnosing and correcting process control problems within a process control system, including, for example, auto-tuners, loop analyzers, neural network systems, etc. Process control operators also receive process variable information from the process via one or more process controllers which provide information to the operators about the operation of the process, including alarms generated within the process. This information may be provided to the process control operator via a standard user interface.
Still further, it is currently known to provide an expert engine that uses process control variables and limited information about the operating condition of the control routines or function blocks or modules associated with process control routines to detect poorly operating loops and to provide information to an operator about suggested courses of action to correct the problem. Such an expert engine is disclosed in U.S. patent application Ser. No. 09/256,585 entitled xe2x80x9cDiagnostics in a Process Control System,xe2x80x9d which was filed on Feb. 22, 1999 and in U.S. patent application Ser. No. 09/499,445 entitled xe2x80x9cDiagnostic Expert in a Process Control System,xe2x80x9d which was filed on Feb. 7, 2000, both of which are hereby expressly incorporated by reference herein. Likewise, it is known to run control optimizers, such as real time optimizers, within a plant to optimize the control activities of the process plant. Such optimizers typically use complex models of the plant to predict how inputs may be changed to optimize operation of the plant with respect to some desired optimization variable such as, for example, profit.
On the other hand, maintenance personnel who are primarily responsible for assuring that the actual equipment within the process is operating efficiently and for repairing and replacing malfunctioning equipment, use tools such as maintenance interfaces, the AMS application discussed above, as well and many other diagnostic tools which provide information about operating states of the devices within the process. Maintenance persons also schedule maintenance activities which may require shut down of portions of the plant. For many newer types of process devices and equipment, generally called smart field devices, the devices themselves may include detection and diagnostic tools which automatically sense problems with the operation of the device and automatically report these problems to a maintenance person via a standard maintenance interface. For example, the AMS software reports device status and diagnostic information to the maintenance person and provides communication and other tools that enable the maintenance person to determine what is happening in devices and to access device information provided by devices. Typically, maintenance interfaces and maintenance personnel are located apart from process control operators, although this is not always the case. For example, in some process plants, process control operators may perform the duties of maintenance persons or vice versa, or the different people responsible for these functions may use the same interface.
Still further, persons responsible and applications used for business applications, such as ordering parts, supplies, raw materials, etc., making strategic business decisions such as choosing which products to manufacture, what variables to optimize within the plant, etc. are typically located in offices of the plant that are remote from both the process control interfaces and the maintenance interfaces. Likewise, managers or other persons may want to have access to certain information within the process plant from remote locations or from other computer systems associated with the process plant for use in overseeing the plant operation and in making long term strategic decisions.
Because, for the most part, very different applications used to perform the different functions within a plant, e.g., process control operations, maintenance operations and business operations are separated, the different applications used for these different tasks are not integrated and, thus, do not share data or information. In fact, many plants only include some, but not all, of these different types of applications. Furthermore, even if all of the applications are located within a plant, because different personnel use these different applications and analysis tools and because these tools are generally located at different hardware locations within the plant, there is little if any flow of information from one functional area of the plant to another, even when this information may be useful to other functions within the plant. For example, a tool, such as a rotating equipment data analysis tool, may be used by a maintenance person to detect a poorly functioning power generator or piece of rotating equipment (based on non-process variable type data). This tool may detect a problem and alert the maintenance person that the device needs to be calibrated, repaired or replaced. However, the process control operator (either a human or a software expert) does not have the benefit of this information, even though the poorly operating device may be causing a problem that is affecting a loop or some other component which is being monitored by the process control operation. Likewise, the business person is not aware of this fact, even though the malfunctioning device may be critical to and may be preventing optimization of the plant in a manner that the business person may desire. Because the process control expert is unaware of a device problem which may be ultimately causing poor performance of a loop or unit in the process control system and because the process control operator or expert assumes that this equipment is operating perfectly, the process control expert may misdiagnose the problem it detects within the process control loop or may try to apply a tool, such as a loop tuner, which could never actually correct the problem. Likewise, the business person may make a business decision to run the plant in a manner that will not achieve the desired business effects (such as optimizing profits) because of the malfunctioning device.
Due to the abundance of data analysis and other detection and diagnostic tools available in the process control environment, there is a lot of information about the health and performance of devices available to the maintenance person which could be helpful to the process operator and the business persons. Similarly, there is a lot of information available to the process operator about the current operational status of the process control loops and other routines which may be helpful to the maintenance person or to the business person. Likewise, there is information generated by or used in the course of performing the business functions which could be helpful to the maintenance person or the process control operator in optimizing the operation of the process. However, in the past, because these functions were separated, the information generated or collected in one functional area was not used at all, or not used very well in other functional areas which led to an overall sub-optimal use of the assets within process plants.
A process control system collects data or information pertaining to the assets of a process plant from various entities of the plant at varying levels of hierarchy. The entities may include field devices such as valves, positioners, switches, multiplexers, transmitters, sensors, control systems, transceivers, variable speed drivers, actuators, I/O systems, two-, three-, or four-wire devices, etc., as well as various smart devices including devices according to a specific protocol such as Fieldbus, HART, PROFIBUS(copyright), WORLDFIP(copyright), Device-Net(copyright), AS-Interface, and CAN. The devices may also include network communication devices such as TCP/IP protocol devices, Ethernet devices, and internet devices. The entities may further include field equipment such as power generation equipment, power distribution equipment, transformers, tanks, rotating equipment, measuring equipment, pumps, etc. Still further, the entities may include groups of devices and/or equipment such as loops, sub units, units, areas or other process control entities. Data and information from these devices, such as process and maintenance data, is manipulated in a coordinated manner by tools, such as an index computation device and modeling tools to create use indices which relate to the status of the entity. For example, information or data may be collected pertaining to the health, variability, performance or utilization of a device, loop, unit, etc. to create a use index relating to the status of the entity. This information may then be sent to and displayed to a process operator, maintenance person or other user to inform that person of a current or future problem. This same information may be used by the process operator to execute a variety of decisions related to the system or individual entities. Alternatively, the system itself may execute such decisions automatically. The process control system may generate indices pertaining to non-process variables, such as the health, performance, utilization and variability of a device, unit, loop, etc.
Still further, some entities may be combined to create a higher level entity and the use indices of the entities may be combined to generate use indices for the higher level entity. Alternatively, models of various entities may be interconnected to generate new models of a higher level entity. The operations of the entity may be simulated to provide new data or information which may be used to create a use index indicating the status of the higher level entity.
Still further yet, a representation of the entities may be displayed with a corresponding use index for each entity. A description may be provided for the benefit of the user to explain the meaning of a particular value for the use index to explain the status of the entity. This description may be used to inform the user of a current or future problem, how to correct the problem, how to optimize the entity, etc. A representation of a higher level entity which includes the entities may be displayed along with its corresponding use index. The representations of the entities may together make up a representation of the higher level entity. The control operator or other user may be permitted to switch between the representation of the higher level entity and a representation of one of the entities making up the higher level entity to allow for viewing of various hierarchical levels within the process control system.